Generic medical instruments are often used in the art as gripping, holding, and/or cutting tools. Thus the jaw members can comprise blades for severing tissue or blunt surfaces for holding severed tissue, for instance, or to clamp off blood vessels.
A common element among these medical instruments is that both jaw members of the tool mounted on the distal end of the shaft can rotate around a common point of rotation. For opening and closing the jaw members, a push-pull rod is provided which is coupled with a movable gripping member of the handle.
Such a generic medical instrument is described for instance, in DE 299 11 011 U. In this known medical instrument the coupling points of the jointed gear are contiguous with the respective jaw members at a distance from the common point of rotation of the jaw members, so that, when the push-pull rod is slid forward, in particular to close the tool, the result is a gear ratio that allows a great transmission of force. These medical instruments have proved themselves in practice; however, in tight spaces—for instance, in endoscopic surgery—that have the disadvantage that the jointed gear in opening the jaw members rotate outward and thus greatly increase the diameter of the instrument in the area between the push-pull rod and the tool. This required space, however, is not always available and thus these known instruments cannot be employed in all operations.
Consequently it is the object of the invention to design a medical instrument of the aforementioned type in such a way that the instrument can be used even in closely confined spaces and with sufficient transmission of force.